Wiper systems for motor vehicles are fastened to the body of a motor vehicle by means of a wiper support, a so-called mounting plate. The mounting plate supports a wiper drive mechanism with a wiper motor and a linkage built onto it whose drive shaft, as a rule by way of a crank and connecting rods, drives cranks that are connected to a drive shaft for each wiper. As a rule, the linkage housing is attached to a motor support of the mounting plate with three screws. The screws engage in protruding screw fittings of a drive-side housing cover with which the linkage housing is supported on the motor support.
The drive shaft of the wiper is supported in a wiper bearing whose bearing housing is fastened to the wiper support or formed onto it. This wiper support is attached to the vehicle body directly by way of the wiper bearing or by way of fastening eyelets that are formed onto the wiper bearing, the wiper support, and/or the motor support.
German utility model 74 34 119 has disclosed a wiper support that is made of a square tube to which a plate is welded that serves as a motor support. Wiper supports of this kind, often called tubular mounting plates or tubular frame systems, are very stable despite a lightweight construction. For cost reasons, a straight support tube is desirable since no prior bending work is required.
A wiper support has also been disclosed by EP 0 409 944 B1, in which a motor support connects tubular parts by way of form-fitting connections. The essentially straight tubular parts have noise-damping, frequency-filtering, or noise-absorbing intermediary parts inserted into them in order to damp noise that is transmitted by the wiper motor via the wiper support onto the wiper bearings and from there, into the vehicle body. A variant demonstrates that the motor support can be embodied in one piece with a housing cover of the linkage housing.
In addition, the journal xe2x80x9cWerkstatt und Betriebxe2x80x9d [workshop and operation] Carl Hanser Verlag Munich, 1995, pp. 812 to 815, and the special edition from the journal xe2x80x9cMetallumformtechnikxe2x80x9d [metal shaping techniques], Claus Dannert Verlag, 1994, under the title xe2x80x9cPrazisions-Werkstucke in Leichtbauweise, hergestellt durch Innenhochdruck-Umformenxe2x80x9d [precision lightweight work pieces produced using internal high pressure shaping] have disclosed a process for shaping tubes into work pieces. This process, which is primarily used for the automotive industry, operates with high pressures. The tubular piece to be shaped is placed in a split molding tool which has the desired work piece mold incorporated into it. The molding tool, which is mounted in a press, is closed by means of a vertically acting press tappet. The tube ends are closed by closing tools, through which a pressure medium is supplied, which presses the tube walls against the inner tool mold. An axial pressure is exerted on the tube by horizontally acting tappets, which overlaps with the internal pressure. Consequently, the material which is required for the shaping is supplied not only from the wall thickness of the tube, but also through the shortening of the tube. The closing tools are guided so that they axially follow this shortening of the tube during the shaping. It is the subject of a prior patent application to also use a process of this kind for the manufacture of a tubular wiper support with different cross sectional shapes.
According to the invention, the hollow profile of the wiper support is guided between at least one screw fitting on one side and the bearing dome of the linkage housing on the other and is secured by means of a retention device, e.g. in the form of a cover plate, screw, or the like. It is supported against the circumference surfaces of the screw fittings and the bearing dome and against the counter support of the linkage housing over a longer region, which extends in the longitudinal direction of the screw fittings. It is therefore secured against rotation. This can be achieved by virtue of the fact that the outer contour of the hollow profile follows the inclination of the screw fittings and the bearing dome. The inclinations of the circumference surfaces of the screw fittings and the bearing dome depend primarily on the manufacturing process when the linkage housing is produced for example by means of a casting process.
In the axial direction, the hollow profile is likewise secured in relation to the linkage housing in a form-fitting manner, by virtue of the fact that it has indentations in the vicinity of the screw fittings and/or the bearing dome, and these indentations partly encompass the screw fittings or the bearing dome. With otherwise circular cross sectional profiles, the indentations also produce a longer contact of the hollow profile along the screw fittings or the bearing dome.
Another possibility for axially securing the hollow profile in relation to the linkage housing is comprised in that the hollow profile has a continuous cross sectional reduction in the vicinity of the screw fittings and the bearing dome, whose shoulders rest against the circumference contour of the screw fittings and/or against the edges of the retention device. In order to embody the form-fitting connections so that it is free of play, is advantageous to clamp the hollow profile between the screw fittings, the bearing dome, and the retention device by means of a certain initial stress.
According to one embodiment of the invention, the screw fittings and the bearing dome are connected to each other by means of housing ribs. The housing ribs on the sides of the hollow profile that are respectively remote from the screw fittings and the bearing dome constitute a counter support for the hollow profile in relation to the screw fittings and the bearing down. This counteracts the stress concentrations of the indentations and in addition, the forces are introduced into the linkage housing in a more uniform and favorable fashion so that a very stable connection of the wiper motor and the wiper linkage is achieved.
The wiper support of the wiper system according to the invention is comprised essentially of a dimensionally stable hollow profile with a round or polygonal cross sectional profile, which is advantageously produced using an internal high pressure shaping process and whose ends support the wiper bearing. A separate motor support is not required. The wiper support is also distinguished by a continuous hollow profile in the vicinity of the wiper motor. This results in a high degree of strength and dimensional stability as well as a low manufacture and assembly cost since connecting elements or a welding process to connect the motor support to the wiper support is no longer necessary.
The linkage housing of the wiper system according to the invention is only slightly modified so that on the one hand, it can be attached to the hollow profile of the wiper support by means of the simple retention device and on the other hand is suitable for an attachment to the usual wiper support with a conventional motor support by means of the screw fittings.
In the wiper system according to the invention, the retention device can also be used to support the wiper support by virtue of the fact that it has integrated supports, e.g. a fastening eyelet, for attachment to the vehicle body.